Transmission board and connector assembly made by a combination of a connector and the transmission board

ABSTRACT

A transmission board ( 10 ) comprises a frame body ( 30 ) and a surface board ( 20 ) supported by the frame body ( 30 ) and having a transmission circuit. The frame body ( 30 ) has plugging edges ( 33, 34 ) that project from the edges of the surface board ( 20 ) for guiding the terminals of mating connectors to connection pads on the surface board ( 20 ). The plugging edges have guiding slopes  33 A and  33 B, and  34 A and  34 B. At least the plugging edges of the frame body ( 30 ) are made of a metal or resin molding.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a transmission board having atransmission circuit on a surface thereof and connection pads on thesurface edge for connection with a mating connector and a connectorassembly consisting of a connector connected to the transmission board.

[0003] 2. Description of the Related Art

[0004] Generally, a transmission board includes a resinous circuit boardwith transmission circuit or circuits printed on one or both sidesthereof and connection pads provided on an edge of the circuit board forconnection with a mating connector. Such a transmission board isdisclosed in U.S. Pat. No. 6,171,115; FIGS. 1-2. The edge of the circuitboard is tapered so as to facilitate connection between the connectionpads and the spring contacts of terminals for a mating connector. Thetapered edge is made by planomilling.

[0005] The above circuit board, however, has the followingdisadvantages.

[0006] First of all, the processing precision of the tapered edge isvery low and the processing requires much labor. The circuit board is sothin that it tends to warp and vibrate upon milling, providing a wavingtapered edge or asymmetrical tapered edges on both surfaces. That is,the processing precision is so low that a plurality of terminals havedifferent plugging forces and contact pressures. In addition, theprecision in the size of the board itself or the positions of connectionpads is so low as to produce a difference between the terminals and theconnection pads, preventing miniaturization of a multiple pole connectorthat has multiple connection pads at high density.

[0007] In general, the circuit board is reinforced by mixing glassfibers. When the edge of a circuit board is planomilled, glass fibersproject at the tapered portion or powder of the glass fiber or resinadheres to the terminal, making poor contact. The rough surface of thetapered portion prevents smooth movement of the terminals, increasingthe plugging force of a multiple terminal connector.

[0008] Where transmission circuits are provided on both surfaces of acircuit board, the dielectric loss, which is produced by the resinbetween the transmission circuit, is so high that the electricalcharacteristics become poor. Especially, this affects the high-speedtransmission. It is noted that the relative permittivity of the resin toair is approximately 4.

SUMMARY OF THE INVENTION

[0009] Accordingly, it is an object of the invention to provide atransmission board capable of being made with high precision so as toplug to a mating connector smoothly, permitting high density terminalarrangement, and improving the electrical characteristics and aconnector assembly that is made up of a connector connected to thetransmission board.

[0010] According to the first aspect of the invention there is provideda transmission board capable of achieving the above object and,according to the second and third aspect of the invention, there isprovided a connector assembly for realizing the above object.

[0011] First Aspect of the Invention

[0012] The transmission board has a transmission circuit provided on asurface and connection pads provided on an edge thereof for connectionwith a mating connector. The edge is provided with a guiding slope forfacilitate contact of a terminal of the mating connector with theconnection pad. According to the invention, the transmission boardcomprises a frame body and a surface board supported by the frame bodyand having a transmission circuit on a surface thereof. The frame bodyis provided with a plugging edge that project from the edge of thesurface board for guiding the terminal of the mating connector to theconnection pad. The plugging edge has a guiding slope and at least theplugging edge of the frame body is made of a metal or resin molding.

[0013] As a result, the plugging edge is made with high precision sothat it is possible to make efficiently a number of frame bodies with noor few variations and with smooth surface. The position of theconnection pads relative to the frame body becomes accurate which, inturn, makes accurate the positional relation between the transmissionboard and a mating connector, making it possible to arrange a number ofconnection pads with high density. In addition, the smooth surfacepermits the connector terminal to slide with low friction, resulting inthe low plugging force.

[0014] A pair of surface boards on which corresponding transmissioncircuits are provided are held by the frame body at a regular intervalsuch that the corresponding transmission circuits are opposed to eachother so as to provide a transmission board for a signal pair. It ispreferred that the opposed transmission circuits are made so as to havea characteristic impedance of approximately 100 ohms in the differentialoperation of the pair. The two surface boards cooperate with the framebody to define a hollow space between them that is filled with air or amaterial having a relative permittivity and a dielectric loss tangent toprovide a transmission board having small loss and the improvedelectrical characteristics. Where a pair of the surface boards areattached to the frame body such that the ground and signal circuits areprovided on the outside and inside thereof, respectively, the signalcircuit is connected through the surface board to the connection padthat is provided on the outside.

[0015] A projecting guide projects from the plugging edge in theplugging direction to enter in the groove of a mating connector beforethe connector terminal abuts against the plugging edge. Also, itprojects from the plugging edge in the vertical direction, forming aridge portion. Upon, plugging with a mating connector, the projectingguide brings the plugging edge to a regular position prior to theplugging, thereby eliminating forcible plugging and damage to theconnection pad. Where the projecting guide is tapered in both thevertical and horizontal directions, insertion into the mating connectoris made easy. The ridge portion makes close contact with thecorresponding groove of a mating connector so that the position of thetransmission circuit is made accurate in the vertical direction, makingeven the contact pressure on the connection pad. Even if thetransmission board is forcibly plugged, only it is tilted at the ridgeportion, and no damage is made to other parts. It is preferred that theinside transmission circuit is connected to the connection pad throughthe surface board at a position relatively close to the edge, therebyeliminating an ad-hoc or stub in the transmission circuit and minimizingthe attenuation or transmission loss at high-speed transmission.

[0016] An extended contact of a metal may be attached to the connectionpad. It is preferred that it is bent in a U-shape at the plugging edgeto reach the guiding slope for protecting it. The signal connection padis positioned relatively closely to the plugging edge and the groundconnection pad is apart from the plugging edge but adjacent to thesignal connection pad such that the extended portion is aligned with thesignal connection pad. As a result, it is sufficient that the groundterminal of a mating connector is made only slightly longer than thesignal terminal, thereby minimizing the connector in the pluggingdirection.

[0017] In order to reduce the plugging force, the guiding slopes aremade so as to have different sloping angles in correspondence withrespective connection pads. Alternatively, the guiding slopes havingdifferent sloping angles or the same sloping angle may be offset in theplugging direction. Consequently, the rate of flexure of the individualterminals on the guiding slopes are different, minimizing the pluggingforce.

[0018] It is preferred that the plugging edge is made higher than thesurface board on the side adjacent to the surface board so that theconnector terminal does not abut against the edge of the connection pad,minimizing the damage thereto. At least one of the projecting guides ismade so as to have a cross-section different from those of the otherprojecting guides, thereby preventing plugging error of the transmissionboard.

[0019] It is preferred that the frame body is provided with a stopperportion to abut against the mating connector at the predeterminedplugging position of the transmission board, thereby preventing damageto the transmission board and connector. Also, it is preferred that theframe body is provided with a lock member for preventing separation fromthe mating connector. Where the frame bodies are provided with a slitinto which a linking member is inserted, it is possible to link themwith the linking member and connect them to a mating connector at once.In order to determine the relative position of the surface board and theframe body, they are provided with a hole or notch and a boss orprojection, respectively, which are deformed under heat and pressure toattach the surface board to the frame body accurately and firmly. Theframe body may have a plurality of plugging edges for plugging toconnectors in correspondence with the surface board having connectionpads arranged along a plurality of edges.

[0020] Second Aspect of the Invention

[0021] The second aspect of the invention relates to a connectorassembly consisting of a plurality of the transmission boards to aconnector. It has transmission circuits on a surface thereof, along theedge of which a connection pads are arranged as part of the transmissioncircuits so that upon connection to the connector, the connection padsare brought into contact with the connector terminals.

[0022] According to the second aspect of the invention, the transmissionboard comprises a frame body and a surface board supported by the framebody and having connection pads arranged along a plurality of edges ofthe surface board on which transmission circuits are provided. At leastthe plugging edge of the frame body is made of a metal or resin molding.A connector is plugged to the transmission boards the plugging edge thatcorresponds to one of the edges, with the other edge ready to connect toanother connector.

[0023] Third Aspect of the Invention

[0024] The third aspect of the invention relates to a connector assemblyconsists of a plurality of the transmission boards and a connectorconnected thereto. It has a plurality of transmission circuits on asurface thereof and a plurality of connection pads arranged along theedge of the surface as part of transmission circuits. A guiding slope isprovided on the edge to facilitate contact of the connection terminalswith the connection pads.

[0025] The transmission board comprises a frame body and a surface boardsupported by the frame body and having transmission circuits thereon.The frame body has a plugging edge along the edge of the transmissionboard for guiding the connector terminals to the connection pads. Theplugging edge is provided with a guiding slope. At least the pluggingedge of the frame body is made of a metal or resin molding. A pluralityof the surface boards are held by the frame body such that thecorresponding transmission circuits are spaced at a regular interval.

[0026] Since a plurality of the transmission boards are provided, it ispossible to handle pair signals. The guiding slope guides the connectorterminals to the transmission boards smoothly. It is preferred that thecharacteristics impedance of the opposed circuit patterns indifferential operation has approximately 100 ohms. The two surfaceboards cooperate with the frame body to define a space filled with airor a material having a relative permittivity and a dielectric losstangent lower than those of a glass fiber reinforced epoxy resin toprovide a transmission board having small loss and good electricalcharacteristics. Where the ground and signal circuits are provided asthe transmission circuits on the outside and inside of the surfaceboard, respectively, the signal circuits are connected to the connectionpads on the outside through the surface board. The two plugging edgesare provided along the two edges of a surface board, which areperpendicular to each other, to be plugged to two connectors.

[0027] A projecting guide extends from the plugging edge to enter thecorresponding groove of a connector before the connector terminal makescontact with the plugging edge to avoid forcible plugging, therebyprotecting the connection pad. Also, a lock member is provided to engagewith the connector for preventing separation when the connector moves toa predetermined plugging position. The frame body is provided with aslit into which a linking member is inserted so that a plurality of thetransmission boards are held at predetermined intervals by the linkingmember and connected to a connector, making a connector assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a perspective view of a transmission board according toan embodiment of the invention;

[0029]FIG. 2 is an exploded perspective view of the transmission board;

[0030]FIG. 3(A) is a sectional view of a hollow part of the transmissionboard in a plane perpendicular to an arrow A of FIG. 1;

[0031] FIGS. 3(B) and (C) are sectional views of the plugging edge of aframe body in planes parallel to the arrow A;

[0032]FIG. 4(A) is a perspective view of a transmission board accordingto the second embodiment of the invention;

[0033] FIGS. 4(B) and (C) are perspective views of variations to thesecond embodiment;

[0034]FIG. 5 is a perspective view of a connector assembly;

[0035]FIG. 6 is a partially cutout, perspective view of the pluggingedge of a transmission board according to the third embodiment;

[0036]FIG. 7 is a partially cutout, perspective view of the pluggingedge of a transmission board according to the fourth embodiment; and

[0037]FIG. 8 is a sectional perspective view of the plugging edge of atransmission board according to the fifth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] In FIGS. 1 and 2, a transmission board 10 consists of a pluralityof surface boards 20 and a frame body 30. The surface boards 20 have anidentical circuit and are attached to upper and lower sides of the framebody 30 such that a signal circuit 21 and a shield surface or groundcircuit 22 face inside and outside, respectively. Alternatively, thesurface boards 20 may have different signal circuits or only a singlesurface board 20 may be used.

[0039] The surface board 20 has a plurality of signal circuits 21 on asurface thereof and the ground circuit 22 on the other surface. Theshield surface 22 covers almost all the signal circuits 21. Connectionpads 23 and 24 are provided on adjacent two edges of the surface board20 on the side of the shield face 22. The number of connection pads 23or 24 is the same as that of the signal circuits 21 In FIG. 2, theconnection terminals or pads 23 and 24 are provided at one and the otherend of each linear signal circuit 21. A conductive portion 23A or 24A isprovided in an aperture of each connection pad 23 or 24 for connectingthe connection pad 23 or 24 to a corresponding signal circuit 21 (FIG.3).

[0040] In FIG. 3, since the conductive portion 24A is formed in the samemanner, only the conductive portion 23A is shown. A cut-off portion 25is provided in the surface board 20 such that the two edges on which theconnection pads 23 and 24 are provided make a T-shape. The cornerbetween the remaining two edges on which no connection pads are providedis cut off obliquely. A pair of such surface boards 20 are attached toboth sides of the frame body 30 such that the two faces on which thesignal circuits 21 are provided face inside and are opposed to eachother.

[0041] The frame body 30 is made by molding a synthetic resin or metal(light metal) into a rectangular frame as shown in FIG. 2. It has a seatface 31 stepped down from a peripheral face 32 by the thickness of thesurface board 20 for receiving the edge of the surface board 20. Theshape and size of the seat faces 31 are made so that its periphery issubstantially identical with the periphery of the surface board 20. Ithas plugging edges 33 and 34 in correspondence with the edges of thesurface boards 20 on which the connection pads are provided. Theplugging edges 33 and 34 are tapered so that the spring terminals of amating connector (not shown) pass over the tapered plugging edges 33 and34 without difficulty to the connection pads 23 and 24. The pluggingedge 33 or 34 has alternately different slopes 33A and 33B or 34A and34B in correspondence with the connection pads 23 or 24. Alternatively,the plugging edges 33 and 34 may have the same slope.

[0042] Projecting guides 35 and 36 are provided at ends of the pluggingedges 33 and 34 of the frame body 30. Alternatively, separate projectingguides 35 and 36 may be attached to the frame body 30. They extend inplugging directions perpendicular to the longitudinal directions of theplugging edges 33 and 34 and in the vertical direction. They have atapered tip 35A or 36A in both the longitudinal and vertical anddirections. Upon plugging, they enter the guide grooves of a matingconnector to determine the plugging position before engagement with theterminals of the mating connector.

[0043] The surface boards 20 are placed on the seat portion 31 atregular positions and secured to the frame body 30 with an appropriatefastener such as an adhesive. The completed transmission board 10 isconnected to the mating connector as follows.

[0044] In FIG. 1, respective mating connectors (not shown) are pluggedto the transmission board 10 at the plugging edges 33 and 34 as shown byarrows A and B. Since the principle of connection is the same, only theconnector in the plugging direction A will be described below. Theprojecting guides 35 enter the corresponding guiding grooves, bringingthe transmission board 10 to a predetermined plugging position definedin the vertical and horizontal directions. The tapered tips 35Afacilitate the movement into the guiding grooves. The projecting guides35 determine the plugging position without difficulty and forcefulplugging is prevented. Also, a small error in the plugging position iscorrected.

[0045] As shown in FIG. 3(B), the connector terminal has a springcontact section C1. When the contact section C1 is moved toward thetransmission board 10 in the plugging direction A after the projectingguides 35 enter the guiding grooves of the connector, it slides on andpasses over the guiding slopes 33A and 33B while flexing and, then,comes into spring contact with the connection pads 23. Since theconnection pad 23 is connected to the signal circuit 21 via theconductive portion 23A, the contact section C1 is connected to thecorresponding signal circuit 21.

[0046] If the angle of the guiding slope 33B is smaller than that of theguiding slope 33A, the rate of flexing of the contact section C1 on theguiding slope 33B is smaller than that of the guiding slope 33A.Consequently, the plugging force as a whole becomes smaller than that ofthe connector that all of the terminals are flexed at the rate ofguiding slope 33A. In addition, the surface of the contact pad 23 ismade lower than the rear ends of the guiding slopes 33A and 33B so thatno or little damage is made to the edge of the connection pad 23 becausethe contact section C1 does not directly ride on the connection pad. Thecontact section of a ground terminal passes over the edge 33 and comesinto contact with the shield face 22 of the transmission board 10 forgrounding. Similarly, another connector (not shown) is plugged to thetransmission board 10 in the direction B so that both the connectors areconnected electrically via the transmission board 10.

[0047] The second embodiment of the invention will be described withreference to FIG. 4, wherein both the surface board 20 and the framebody 30 are different from those of the first embodiment.

[0048] A plurality of ground connection pads 22A extend from the shieldsurface at opposite ends of the array of connection pads 23.Consequently, it is sufficient for the ground terminals of a matingconnector to be slightly longer than the signal terminals, therebyminimizing the size of the connector in the plugging direction.

[0049] The frame body 30 is provided with a pair of stopper portions 35Bfor bringing the mating connector to a predetermined plugging position,a lock member 37 for preventing separation from the mating connectorafter plugging, and a slot portion 38 for engagement with a linkingmember for linking a plurality of transmission boards as a unit.

[0050] In FIG. 4(A), the stopper sections 35B have a step portion at theplugging edge 33 for abutting on a mating connector to provide thepredetermined plugging position. The lock section 37 has a flexible armwith a hook portion 37A for the plugging edge 34. Upon plugging, thehook portion 37A engages with the mating connector for preventingaccidental separation.

[0051] As shown in FIGS. 4(B) and (C), the lock section 35D is providedon the projecting guides 35 for engagement with a mating connector forpreventing separation from the mating connector. In FIG. 4(B), a slit35E is provided in the projecting guide 35 so that the projecting guide35 is so flexible that the width of the slit 35E is reduced uponplugging and the compression is released upon completion of theplugging, providing a locking condition. In Fig. (C), such flexing isnot made in the projecting guides but in the mating connector. A ridgeportion 35F is provided on the side of the projecting guide 35 forpreventing erroneous insertion of a transmission board.

[0052] As shown in FIG. 5, a linking member 39 is inserted into the slotportions 38 provided in the edges opposite to the plugging edges 34 tounite the transmission boards 10 as an assembly. A connector 40 isplugged to the assembly of transmission boards 10 at the plugging edges34. The linking member 39 is made of a metal in such a shape as to coverthe connector assembly for producing shield effects. Alternatively, theadjacent frame bodies may be designed so as to engage with each other,forming an assembly.

[0053] Other embodiments will be described with reference to FIGS. 6 and7, wherein the plugging force is designed to be minimized. In FIG. 6, asdescribed with reference to FIGS. 1 and 2, two types of guiding slopes33A and 33B, which have different sloping angles, are arrangedalternately. The guiding slopes 33A have a sloping angle smaller thanthat of the guiding slopes 33B so that the terminals of a matingconnector flex on the guiding slope 33A at a lower rate than on theguiding slope 33B. That is, the degree and duration of resistance uponplugging are so different between them that the plugging force as awhole is minimized.

[0054] In FIG. 7, the guiding slopes 33A and 33B, which havesubstantially the same sloping angle, are offset in the pluggingdirection. Consequently, the terminals start to flex at different timesso that the respective plugging forces do not concentrate at the sametime, minimizing the plugging force as a whole.

[0055] The conductive portion 23A is provided relatively closely to theguiding edge 33 in FIG. 6 but spaced farther from the guiding edge 33 inFIG. 7. In the former, there is no ad-hoc or stub (branching) in thetransmission circuit, minimizing the attenuation or transmission loss inthe high-speed transmission and, in the latter, there is no or littledanger that the connector terminal comes to contact with the conductiveportion and it is suitable for the application where no high-speedtransmission is required.

[0056] In FIG. 8, the connection pad 23 is provided on the lower side ofthe surface board 20 on which the signal circuit is provided. Anextended contact 41 is brazed to the connection pad 23. The extendedcontact 41 extends outwardly from the edge of the surface board 20through a slit 33C in the plugging edge 33 of the frame body. It is bentinto contact with the guiding slope 33A for protecting the guiding slope33A. It is brought into contact with the connector terminal C1 at itsbent portion, thus eliminating the above stub problem.

[0057] A variety of modifications may be made to the illustratedembodiments. For example, if both the signal circuits of two surfaceboards are made identical and opposed to each other and thecharacteristic impedance is set at approximately 100 ohms, theelectrical characteristics are improved. The mechanical strength and theelectrical loss are improved by filling the space between the twosurface boards with air or a material having a relative permittivity(∈r) and dielectric loss tangent (tanδ) lower than those of the glassfiber reinforced epoxy resin for the surface boards. The glass fiberreinforced epoxy resin “FR-4” has a relative permittivity of 4.8.

[0058] As shown in FIG. 4(A), a projection 35C is provided on the topsurface of the projecting guide 35 so as to make close contact with thegroove in the mating connector so that the vertical position of atransmission circuit becomes accurate, making even the contact pressureson the connection pads of the two surface boards. Ever if thetransmission board is plugged forcibly, only it is tilted at theprojection 35C and no other parts are damaged. A notch 25 is provided inthe surface board 20 and a boss 39 is provided on the frame body 30 forengagement with the notch 25. The boss 39 is then deformed under heatand pressure to secure the notch 26. The plugging edges may be providedon opposite edges or three edges of a transmission board.

[0059] As has been described above, according to the invention, theframe body is made of a metal of resin molding so that no mechanicalprocessing such as cutting is required, thus improving not only theproductivity but also the accuracy and surface condition of the pluggingedge. As a result, not only the contact pressures of connector terminalsbecome even but also the contact positions become so accurate that theplugging operation is made with small sliding resistance. The highprecision makes it possible to miniaturize the connection pads and theconnector terminal arrangement, providing a compact design.

[0060] Where two parallel surface boards are provided on the frame body,a material with a low relative permittivity, such as air, is providedbetween the surface boards so that the dielectric loss is reduced, thusimproving the electrical characteristics. The linking section providedon the frame body makes it easy to provide a connector assembly that hasa plurality of transmission boards.

1. A transmission board comprising: a frame body; at least one surfaceboard that is supported by said frame body and has at least onetransmission circuit with a connection pad on a surface thereof; atleast one plugging edge that is provided on said frame body and has atleast one guiding slope for guiding a terminal of a mating connectortoward said connection pad; and said plugging edge being made of a metalor resin molding.
 2. The transmission board according to claim 1,wherein a plurality of said surface boards are spaced at a constantdistance by said frame body such that said transmission circuits areopposed to each other.
 3. The transmission board according to claim 2,wherein said opposed transmission circuits have a characteristicimpedance of approximately 100 ohms in differential operation.
 4. Thetransmission board according to claim 2, wherein said surface boardsdefine a layer of air or material having a relative permittivity and adielectric loss tangent that are lower than those of a glass reinforcedepoxy resin.
 5. The transmission board according to claim 2, whereinsaid transmission circuits include at lease one ground circuit and atleast one signal circuit provided on an outside and an inside of saidsurface board, respectively, and said connection pads are provided onsaid outside, with said signal circuit is connected to said connectionpad through said surface board.
 6. The transmission board according toclaim 1, which further comprising at least one projecting guideextending from an end of said plugging edge in a plugging direction suchthat upon plugging with a mating connector, it enters a correspondinggroove of said mating connector before said plugging edge abuts againsta terminal of said mating connector and having at least one raisedportion on a top or bottom face thereof.
 7. The transmission boardaccording to claim 2, wherein said transmission circuit provided on aninside of said surface board is connected to said connection padprovided on an outside at a position relatively close to an edge of saidsurface board.
 8. The transmission board according to claim 2, whereinsaid connection pad is provided with an extended contact that is bent atsaid plugging edge so as to cover said guiding slope.
 9. Thetransmission board according to claim 1, wherein said surface board hasat least one signal circuit provided on an inside thereof and at leastone ground circuit provided on an outside thereof as said transmissioncircuits, and at least one signal connection pad provided on saidoutside close to said plugging edge and connected to said signal circuitthrough said surface board and at least one ground connection padprovided on said outside and spaced from said plugging edge but close tosad signal connection pad, and said ground connection pad provided withan extended portion that is aligned with said signal connection pad. 10.The transmission board according to claim 1, wherein said guiding slopeshave different sloping angles corresponding to said connection pads. 11.The transmission board according to claim 1, wherein said guiding slopesare offset in a plugging direction.
 12. The transmission board accordingto claim 1, wherein said plugging edge has a top face higher than saidsurface board on a side adjacent to said surface board.
 13. Thetransmission board according to claim 1, wherein said frame body isprovided with at least one projecting guide that projects from saidplugging edge in a plugging direction and has a vertical length that islarger than that of said plugging edge.
 14. The transmission boardaccording to claim 13, wherein said projecting guide is tapered in bothvertical and horizontal directions.
 15. The transmission board accordingto claim 13, wherein at least one of said projecting guides has adifferent cross-section from the other said projecting guides in a planeperpendicular to said plugging direction.
 16. The transmission boardaccording to claim 1, wherein said frame body is provided with a stopperportion that abuts against said mating connector when said transmissionboard is plugged to a predetermined position.
 17. The transmission boardaccording to claim 1, wherein said frame body is provided with a lockmember for preventing separation from said mating connector.
 18. Thetransmission board according to claim 1, wherein said frame body isprovided with a slit portion for receiving an engaging portion of alinking member for holding a plurality of said transmission boards atregular intervals.
 19. The transmission board according to claim 1,wherein said surface board and said frame body are provided with a holeor notch and a boss or projection, respectively, for engagement witheach other and deformation under heat and pressure.
 20. The transmissionboard according to claim 1, wherein said frame body is provided with twosaid plugging edges, one of said plugging edges is provided at an endwith a projecting guide that projects in a plugging direction and has avertical width larger than that of said plugging edge.
 21. A connectorassembly consisting of at least one connector and at least onetransmission board connected to said connector, wherein saidtransmission board comprising: a frame body; at least one surface boardsupported by said frame body and having at least one transmissioncircuit and at least one connection pad provided on at least one edgethereof, said frame body is provided with at least one plugging edgemade of a metal or resin molding.
 22. A connector assembly consisting ofat lease one connector and at least one transmission board connected tosaid connector, wherein said transmission board comprising: a framebody; a pair of surface boards each having at least one edge andsupported by said frame body at a regular interval such thattransmission circuits thereof are opposed to each other and, said framebody being provided with at least one plugging edge that extends alongsaid edge, has at least one guiding slope, and is made of a metal orresin molding.
 23. The connector assembly according to claim 22, whereinsaid opposed circuits are made so as to have a characteristic impedanceof approximately 100 ohms in differential operation.
 24. The connectorassembly according to claim 22, wherein said opposed surface boardsdefine, in cooperation with said frame body, a layer of air or materialhaving a relative permittivity and a dielectric loss tangent lower thanthose of a glass reinforced epoxy resin.
 25. The connector assemblyaccording to claim 22, wherein said pair of surface boards have, as saidtransmission circuits, a ground circuit and a signal circuit on anoutside and an inside thereof, respectively, and connection pads on saidoutside, with said signal circuit connected to said connection padthrough said surface board.
 26. The connector assembly according toclaim 22, wherein said frame body is provided with a plurality of saidplugging edges that are provided in correspondence with a plurality ofsaid edges having said connection pads thereon and connectable to aplurality of connectors.
 27. The connector assembly according to claim26, wherein said frame body is provided with at least one projectingguide projecting from said plugging edge in said plugging direction sothat a tip thereof enters a corresponding groove of said connector uponplugging before a terminal of said connector abuts against said pluggingedge and a lock member for preventing separation from said connectorwhen said transmission board engages with said connector at apredetermined position.
 28. The connector assembly according to claim22, wherein said frame body is provided with a slit into which a linkingmember is inserted to link a plurality of said transmission boards.